Ecosystems Unit- Student Reference Notes Ecosystems An ecosystem is formed by all the living and nonliving things that interact together in an environment. Living things could include animals, plants, fungi, and bacteria. Nonliving things could include soil, sunlight, water, and the climate. Food Chains in Ecosystems A food chain shows how living things transfer energy from one species to another within an ecosystem. If one part of a food chain changes or is broken, every other part is affected. A food chain model can be used to explain: The movement of matter among producers, consumers, and decomposers. How animals eat plants and/or other animals for food. How some organisms break down dead organisms and recycle materials back to the air and soil. How plants produce sugars using sunlight during photosynthesis. The food an animal digests contains energy that was once energy from the sun. The food an animal digests provides energy and nutrients for life processes, including body repair, growth, motion, body warmth, and reproduction. Living Things That Are Part of an Ecosystem s Food Chain Producers These are organisms that make their own food. They capture energy from sunlight, and use it in a process called photosynthesis. All plants are producers. Consumers These are organisms that get energy by eating other organisms. There are 4 main types of consumers: 1. Herbivores eat only plants and plant products. Some examples are elephants, deer, insects, gorillas, and cows. 2. Carnivores eat other animals (meat). Some examples are ladybugs, spiders, sharks, hawks, and owls 3. Omnivores eat both plants and animals. Some examples are crows, raccoons, coyotes, and most humans. 4. Scavengers animals that feed on the bodies of dead organisms. Some examples are vultures, termites, and hyenas. 1
Decomposers organisms that help to break down and decay dead organisms and the waste of living organisms These can be bacteria or fungi - Decomposers use up what scavengers leave behind. Predator a carnivorous animal that hunts, kills, and eats other animals in order to survive. Prey an animal that is caught, killed, and eaten by another animal for food 2, 3, 4, 1, 5 In the above food chain model, energy is transferred from the sun to producers, consumers, and decomposers. 1. First the sunlight shines on the grass (producer) which absorbs it. The grass uses sunlight, water, and carbon dioxide to produce food (sugars) for the plant during photosynthesis. 2. Next a grasshopper (herbivore) will eat the grass, and the energy moves from the grass to the grasshopper. 3. Then the energy flows to the snake (carnivore) when it eats the grasshopper. 4. Energy then moves to the hawk (carnivore) when it eats the snake. 5. When these organisms die, decomposers such as fungi help break them down and recycle materials back to the soil. This makes the soil more fertile (rich) and plants use the nutrients to grow. 2
Food Webs in an Ecosystem A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All the interconnected and overlapping food chains in an ecosystem make up a food web. Changes in Ecosystems An ecosystem and its food chains are delicately balanced. Each part depends on the other parts. Even a small change can upset the balance and affect the whole ecosystem. For example: If a drought occurs (a long period of unusually dry weather), plants won t have enough water to grow. Animals that eat those plants would have to leave the area or starve. A forest fire might burn the trees in an area, causing many animals to lose their homes and have to leave. But, over time, new plants will thrive on the forest ground because the tall trees are no longer blocking their sunlight. Ash also adds new nutrients to the soil, making it richer. Humans use part of the land in an area to build a landfill. This reduces the size of the existing plant and animals habitats, and some are forced to move away. Pollutants from trash leak into the ground water, and plants and animals die. 3
Too much fishing takes place in one area of water, causing a large decrease in the fish population. Animals that eat the fish don t have enough food. They move away or starve. Invasive species are living organisms that are introduced to a new and different ecosystem from which the invasive species originated and typically cause damage to this new ecosystem. They can use up the resources of the ecosystem, making survival more difficult for the living things which naturally inhabit that ecosystem. Examples of Unique Ecosystems Desert: A place that receives less than 10 inches of rain per year is a desert. Typically, the climate is hot and dry, but cold deserts also exist. Organisms adapted to live in the desert: Cactus plants have needlelike spines that do not let much water escape and long roots to absorb more water from the ground. A cactus stores water in its large stem, and its waxy covering reduces the amount of water that escapes into the air. Camels have extra-long eyelashes and a special eye covering to protect their eyes from desert sand. They store fat in their humps, which can become an energy source. Their large, broad feet do not sink into the sand. Polar Region: A polar ecosystem is characterized by extremely cold temperatures, lots of ice and snow, and strong winds. Some polar regions are also deserts because they receive so little rain. Organisms adapted to live in the polar region: A polar bear has hairy soles on its feet to insulate its paws and provide traction on ice. It has a small tail and small ears to reduce the amount of body heat the bear loses. It has a thick layer of fat, blubber, under its waterproof fur to keep it warm. Its white fur color helps it to blend in with the snowy surroundings while its black skin absorbs heat to keep it warm. Lichens are a flower that is able to survive drought and cold. They settle in places with the most sunshine, but also in cracks between rocks so that snowflakes are captured in the cracked rock and can be absorbed for water. With their dark color, the lichens absorb more light. Rainforest: A rainforest is a thick, dense jungle habitat. It has tall trees, lots of rainfall, high humidity, and warm temperatures. 4
Organisms adapted to live in the rainforest: Howler monkeys have a very loud call, alerting predators that can t see them in the dense trees to stay away. They live in the tops of trees and get most of the water they need from the food they eat. They very rarely need to climb down to the ground. They can use their tails to grip branches, like having a fifth limb. Rafflesia are the largest flowers in the world. They grow on the rainforest floor where there is little sunlight and have no roots, stems, or leaves. Acting as parasites, they instead get all of the nutrients and support they need by attaching themselves to other vines growing nearby. They also have the foul smell of rotting flesh, which attracts scavenger insects for pollination. Characteristics of Living Things All Living Organisms Must Do the Following... G Grow and develop through a life cycle R Reproduce more of its species R - React to changes in its environment E Energy is taken in and used W Waste is given off Butterfly Life Cycle Life Cycles: All animals go through predictable life cycles that include birth, growth, development, reproduction, and death. Examples of unique life cycles: Both butterflies and frogs undergo metamorphosis. Metamorphosis is the process of a young animal s body changing significantly into its adult form. 5
Frog Life Cycle The Parts of a Plant Living Things Can Be Plants Roots Absorb water, nutrients, and minerals from the soil; Help anchor the plant in the soil Stem Transports water and nutrients throughout the plant; Helps support the plant Leaves Absorb the sunlight that is used for photosynthesis to make food for the plant Flower Produces the fruit where the seeds are held to produce new plants; the reproductive part of a plant Seed Contains an embryo of a new plant. Seeds are dispersed (spread) by wind, water, animals, and humans. Fruit Protects and holds the seeds 6
Photosynthesis The process of plants making food from sunlight, carbon dioxide, and water. Photosynthesis happens in the plant s leaves. The Life Cycle of a Plant 1 2 3 4 5 Seeds are planted by people or scattered by wind, water, and animals. Seed begins to germinate. Seed coat splits and plant sprouts. Seedling begins to mature and roots, stem, and leaves develop. Flowers begin to bloom. Seeds or fruit begin to develop. How Are Traits and Behaviors Passed Along in Living Things? Adaptation Structures and behaviors that help organisms survive in their surroundings Inherited Traits Traits that are passed from parents to offspring Example: A baby elephant inherits the traits of having four sturdy legs, two big floppy ears, and a long trunk from its parents. Instinctive Behavior A behavior that an animal inherits from its parents Example: Salmon make a difficult journey, traveling upstream, to return to their birth place to lay their eggs. Structural Adaptation A body part that does a certain job for an organism Example: A hawk has sharp claws for killing prey. Behavioral Adaptation A specific behavior that helps an organism survive that may or may not be inherited Example: Squirrels gather extra food and store it for the winter. Learned Behavior A behavior that an animal develops by observing other animals or being taught, not by inheriting it Example: A dog can learn to sit or roll over. 7
How Do Animals Adapt to their Ecosystem? Changing Bodies Evolution -This is a long process during which the body of an animal changes slowly over generations. Species are always evolving. Over millions of years, these changes allow the animal to adapt to its habitat. Adapting to the Seasons Insulation - In the winter some animals grow more fur or hair, called insulation, to adapt to the colder weather. Shed - When the warmer seasons come, animals lose, or shed, their added fur. Hoard - Some species have learned to store, or hoard, extra food for the times when it is not easily available. For example: squirrels gathering acorns Hibernation - Some animals go into a deep sleep rather than storing or finding food for the winter. Taking a Long Trip Migration - Some species travel from one place to another when the seasons change. Many birds, whales, fish, and deer migrate to different habitats to adapt to the changing seasons. Some migrate in order to find food; others need a warmer climate. Skein - This is the V formation that birds fly in when migrating. It creates an air pattern that allows the birds in the back of the pack to use less energy.. Staying Warm in a Cold Climate Blubber - This is a thick layer of fat that helps keep the bodies of seals, whales, and walruses warm. Other adaptations: Polar Bears - The hair of the polar bear is hollow to let in more heat and their skin is black to better absorb heat. Arctic Fox - This animal has tiny ears to keep in more of its body heat. Keeping Cool in a Hot Climate Storing Water - Desert animals, such as camels, must store moisture in their body. Nearly all animals release water in their urine, but kangaroo rats have urine that is so dry it is powder instead of liquid. Burrows - Desert animals, such as tortoises and toads, hide from the sun during the day in underground spaces called burrows. Estivate - During the hottest, driest months some animals go into a deep sleep, similar to hibernation, to escape the heat. 8
Adapting to the Dark Echolocation This is like Sonar. An animal sends high-pitched sounds that travel long distances and then bounce back to tell them the size and location of an object ahead. Dolphins and bats use echolocation. Singing underwater - Whales sing songs to stay in contact when they cannot see each other. Tentacles - Some animals use these to find food. Tapetum - Owls have this layer in their eyes to improve their night vision because any light that hits the tapetum is reflected back onto the object. Hiding Out Camouflage - Colored markings on the body allow animals to blend in with their surroundings. For example, Arctic Hares are white in the winter and brown in the summer. Fooled You Mimicry - Some animals mimic, or copy, things in their environment to protect themselves from predators. For example, the animal s body could look like something in nature, such as a leaf or a rock. Or the animal might change its behavior and pretend to be something it is not. An opossum plays dead to avoid predators. In their Defense Body Armor - Some animals have body armor, such as sharp spikes or a protective shell. Musk - An awful smelling fluid that animals can release to ward off predators. A skunk sprays musk. Venom - Poison that an animal injects into another animal using sharp teeth called fangs. Snakes are often venomous. 9